During the coming year we propose to carry out studies in the following research areas: 1. Study the properties of the novel actinomycins synthesized by Micromonospora floridensis and to determine the chemical nature of the amino acid constituents of the antibiotics. 2. Conduct biochemical and genetic studies with respect to the pathway of tryptophan catabolism and to investigate the regulatory controls that influence the synthesis and activity of the enzymes of this pathway. 3. Study the mechanism of biosynthesis of D-amino acids, imino acids, and N-methylamino acids. 4. Study cell-free synthesis of actinomycin. 5. Further investigate the relationship of actinomycin formation to the growth of the producing organism. The mechanism of resistance of the producing organism, S. parvulus, to actinomycin will be investigated.